1. Field of the Invention
The present invention relates to a radio selective calling receiver and, more particularly, to a radio selective calling receiver which outputs a message corresponding to a received stereotyped expression by speech.
2. Description of the Prior Art
When a conventional radio selective calling receiver of this type receives a radio selective call signal addressed thereto, the receiver receives a message signal succeeding the call signal, restores it to a message, and outputs it by speech through a loudspeaker or by display through an LCD.
This received message signal is constituted by an abbreviated code representing a stereotyped expression, an illustration, or the like, and numerical information. On the transmission side, a code table or the like is prepared to edit a message, and a message signal corresponding to the message is transmitted through a telephone set such as a push-button phone. In some system, speech information is directly converted into a digital signal without using any stereotyped expression as a message signal, and the digital signal is transmitted. On the reception side, this signal is restored to analog speech information and output by speech.
When a message is output by speech in this manner, the power consumption undesirably increases. In a radio selective calling receiver of this type, in particular, miniaturization and weight reduction are important requirements from the user's point of view. It is therefore inevitable that the capacity of the built-in battery is small, and the power consumption must be reduced.
For this reason, in the receiver disclosed in Japanese Unexamined Patent Publication No. 5-244061, the presence/absence of speech information in a received message signal and the data amount of speech before the information is output by speech. A callee sees this display to suppress unnecessary speech output and reduce the power consumption.
In this prior art, a message signal is constituted by speech information obtained by converting speech into digital information, numerical information, and the like. If this signal includes no speech information, the user does not perform a speech output operation. Alternatively, if the data amount of speech is known, since the output time can be expected, a speech output less irritates the user. In some case, it suffices if the speech information is partly output. Therefore, a reduction in power consumption can be attained as well as an improvement in operability.
As described above, in the prior art, in order to reduce the power consumption, the presence/absence of speech information included in a message signal and the length of the information are displayed before the information is output by speech. If, however, the user of this receiver has a visual or auditory handicap or cannot see the display in a dark place, this function cannot produce any satisfactory effect.
Furthermore, in the prior art, as a means for detecting the presence/absence of speech information and its length, speech information is read out from a memory, and its data amount is measured. However, this means demands a complicated circuit.